Building air infiltration, the uncontrolled leakage of air in and out of buildings, accounts for over 30% of total heating load of commercial buildings in the US. Measuring the infiltration in commercial buildings is difficult because of the physical size and measurements cannot be made during construction which means sealing the building becomes more difficult and expensive.
Two methods for measuring building infiltration are currently used: pressurization testing and tracer gas testing. Pressurization testing works by pressurizing an entire building or building section with fans and measuring the air flow through and pressure difference across the envelope. This method works well for small buildings but is impractical for large buildings. Further, the entire building envelope must be constructed before the method can be used. The tracer gas method works by introducing a gas into a room at a known rate and measuring the amount of time for the gas concentration to be reduced through infiltration and exfiltration. The tracer technique can take a very long time (especially on buildings with low infiltration), is more difficult to apply in large buildings, and also needs a completed building enclosure to utilize.
Others have attempted to correlate sound transmission loss to infiltration rates with limited success. While correlations do exist, they are specific to the exact details of wall construction and infiltration location so one cannot develop correlations on one building and use them on another and hence the method cannot be used as a general method for measuring infiltration. Further, there is no general method on how to estimate the correlations without actual measurement of the building (i.e. from drawings and computer models).
Leakages in a gas-storing containers and air-conditioned buildings are serious safety and economic problem to the society. However, the present leakage detection methods such as smoke stick method are not very effective and involves a lot of human resource.